Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Poster Session I
HL 13.38: Poster
Montag, 12. März 2018, 17:30–19:30, Poster B
Theoretical analysis of optical properties of Cu2ZnSn(S,Se)4 solar absorbers. — •Sergii Zamulko1, Kristian Berland1, and Clas Persson1,2 — 1Centre for Materials Science and Nanotechnology, University of Oslo, P. O. Box 1048 Blindern, NO-0316 Oslo, Norway — 2Department of Materials Science and Engineering, Royal Institute of Technology, Brinellvägen 23, SE-100 44 Stockholm, Sweden
Kesterite Cu2ZnSn(SxSe1-x)4 are attracting much attention for application in thin film solar cells, as they consist of earth-abundant elements and operate in a favorable size of band-gap. In this work, we study the dielectric functions of this compound for different alloy composition 0 < x < 1. Results of ellipsometry measurements are compared with density functional theory (DFT) calculations. The calculations were performed at three levels of theory, using a generalized gradient approximation (GGA), meta-GGA - both relying on on-site +Ud Coloumb correction - and a hybrid functional approach. Furthermore, using a recently developed k.p interpolation scheme, we show that a dense Brillouin zone sampling is needed to accurately account for the shape of the dielectric function. Comparing experimental and theoretical data with enhanced numerical accuracy sheds light on how the critical points in the real part of dielectric function shifts as a function of sulfur content.